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    <meta charset="UTF-8">
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    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>
    
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<script>
    // 都属于 number 类型
    // NaN  非数字
    // Infinity  正无限 无穷大

    var a = "10a";
    var b = 3;
    var c = a * b;
    console.log(c,typeof c); 


    var a = -1;
    var b = 0;
    var c = a / b;  // 1 / 0
    console.log(c,typeof c);  //  Infinity





</script>
</html>